Origins of Neanderthal DNA in humans

Long ago, early humans shared the earth with several archaic human species, including Neanderthals and Denisovans. These species, were bipedal and close relatives of modern humans. They lived in parts of Northern Africa, Europe, and Asia, while the first populations of modern humans, Homo sapiens , lived in the Horn of Africa. Eventually, as those humans began migrating out of Africa, some came across these archaic human species, and the populations began to interact. At least since the 1990s, archaeologists have suspected there had been interbreeding between humans and Neanderthals, but genetic evidence emerged when the first draft genome of Neanderthals was published in 2010 . Today, we know that an average of 1–3% of the human genome can be traced to Neanderthal ancestry and that the amount varies among people throughout the world. But exactly when that interbreeding occurred remained unclear. Now, thanks in part to ancient DNA sequencing